I think deer stalking is attracting more newcomers because these days it is seen as a more ethical thing to do and is more popular with the media.
The trend is really not helped by folk such as Hugh Fearnley-whittingstall who write cookery books which present deerstalking as a "truly thrilling, close-to-nature experience" compared to a "ten gun, gin and tonic fuelled pheasant massacre" (direct quotes from his book)
I understand the point he tries to make but what he fails to mention is that driven shooting can be equally sporting, is a very important part of our British heritage, is a traditional way of taking large numbers of keepered birds, is good for the economy and good for the countryside.
I have never been on a driven day because I cannot justify spending that sort of money on one day, but if other people want to spend their hard-earned on it (or do it for free) then great.
For me, rough shooting is a very close second behind deer stalking and I can walk all day, any day, with dog and shotgun on farmland in winter in search of snipe, golden plover, woodcock, rabbit, pheasant, pigeon, duck, et cetera, without a moment of boredom.